Common questions about fentanyl

Fentanyl is from a group of medicines called opioids or narcotics.

It works in the central nervous system and the brain to block pain signals to the rest of the body. It also reduces the anxiety and stress caused by pain.

This depends on the type of fentanyl you take.

A fentanyl injection into a vein gives the quickest pain relief. It works almost straight away and is usually only given in hospital.

Fentanyl tablets, lozenges and nasal sprays take about 15 to 30 minutes to work but they wear off after 4 to 6 hours.

Fentanyl patches can take up to a day or 2 to start working but they'll last longer. Patches are usually given after fentanyl tablets. This is to make sure that you have pain relief from the tablets until the patches start to work.

Some people with conditions that need long-term pain relief may need to take fentanyl for a long time.

If you need to take it for a long time your body can become used to it (known as tolerance). That means you need higher doses to control your pain over time.

Some people can become more sensitive to pain (hyperalgesia). If this happens, your doctor will reduce your dose gradually to help these symptoms.

It's possible to become addicted to fentanyl. For this reason, your dose will be reviewed to make sure you're only taking the amount you need to control your pain.

Your treatment plan may include details of how and when to stop taking fentanyl.

If you're having treatment for cancer pain or other severe pain, your pain control will be carefully monitored. Speak to your doctor if you're worried about tolerance, hyperalgesia or becoming addicted.

If you're addicted to fentanyl you may find it difficult to stop using it or feel you want to use it more often than you need to.

If you stop taking fentanyl suddenly you may get withdrawal symptoms.

These can include:

• feeling agitated or anxious
• panic attacks
• feeling your heart beat (palpitations)
• difficulty sleeping
• shaking
• sweating
• body aches
• feeling restless

Talk to your doctor if you:

• are worried about addiction
• need help with addition
• want to stop taking fentanyl

If you need to take fentanyl for a long time your body can become used to it, known as tolerance.

This is not usually a problem. However, you could get withdrawal symptoms if you stop taking it suddenly.

If you want to stop taking fentanyl, talk to your doctor first. Your dose can be reduced gradually so you do not get withdrawal symptoms.

If you stop taking fentanyl suddenly it can make you:

• feel agitated
• feel anxious
• shaky
• sweat a lot

Fentanyl acts on different pain signals in the brain to some other opioids.

The pain relief and side effects will be different for everyone. Your doctor may prescribe fentanyl if you've had side effects from other opioids.

The way you take fentanyl is different to some other painkillers. Fentanyl is not absorbed very well by swallowing tablets. Instead your body absorbs it through your skin, your nostrils, under your tongue or the inside of your cheek.

Some people find skin patches more convenient than taking tablets or capsules regularly.

Fold your used patch in half so that the sticky sides stick to each other and then put it back in the packet it came in.

Return any used or unused patches to your pharmacist who will destroy them safely.

Patches can accidentally stick to another person.

Fentanyl does not stop any type of contraception from working, including the combined pill, progestogen-only pill and emergency contraception.

However, if fentanyl makes you vomit, your contraceptive pills may not protect you from pregnancy. Look on the pill packet to find out what to do.

Find out more:

• What to do if you're sick or have diarrhoea when taking the combined pill
• What to do if you're sick or have diarrhoea when taking the progestogen-only pill

Do not drive a car or ride a bike if fentanyl makes you sleepy, gives you blurred vision or makes you feel dizzy, clumsy or unable to concentrate or make decisions.

This may be more likely when you first start using fentanyl but could happen at any time, for example when starting another medicine.

It's an offence to drive a car if your ability to drive safely is affected. It's your responsibility to decide if it's safe to drive. If you're in any doubt, do not drive.

Even if your ability to drive is not affected, the police have the right to request a saliva sample to check how much fentanyl is in your body.

Talk to your doctor or pharmacist if you're unsure whether it's safe for you to drive while taking fentanyl. GOV.UK has more information on the law on drugs and driving.

It's best not to drink alcohol when you first start taking or using fentanyl until you see how it affects you.

Drinking alcohol while using fentanyl will make you more sleepy and increases the risk of serious side effects.

Grapefruit juice can increase the amount of fentanyl in your body so it's a good idea not to drink it.

It's best not to drink alcohol when you first start taking or using fentanyl until you see how it affects you.

Fentanyl is not generally affected by food so you can eat normally.

If you take recreational drugs, such as cannabis, cocaine or heroin, while you're taking fentanyl, you're more likely to get the serious side effects. These include breathing difficulties, heart problems such as high blood pressure, seizure or fits and even going into a coma.

Some recreational drugs, such as cannabis, will also increase the risk of side effects from fentanyl – it may make you feel very sleepy or dizzy.

Taking heroin while you're on fentanyl is especially dangerous. You're more likely to get all the side effects of fentanyl.

Tell your doctor if you think you may take recreational drugs while you're on fentanyl.

You can find out about the side effects of recreational drugs on the Frank website.